Semiconductor nanocrystals and processes for synthesizing the same

Abstract

A nanocrystal particle including: a semiconductor material; boron and optionally fluorine, wherein the particle has an organic ligand bound to a surface thereof, the boron is present as being doped in the particle or as a metal boride and the fluorine is present as being doped in the particle or as a metal fluoride.

What is claimed is: 
     
       1. A nanocrystal particle comprising:
 a semiconductor material; 
 boron and fluorine, wherein the particle has an organic ligand bound to a surface thereof, the boron is present as being doped in the particle or as a metal boride and the fluorine is present as being doped in the particle or as a metal fluoride, 
 wherein the semiconductor material comprises a Group II-VI compound, a Group III-V compound, a Group IV-VI compound, a Group IV compound, or a combination thereof. 
 
     
     
       2. The nanocrystal particle of  claim 1 , wherein the nanocrystal particle comprises a core comprising a first nanocrystal and a shell surrounding the core and comprising a crystalline or amorphous material, and at least one of the boron and the fluorine is present as being doped in the core, the shell, or the both. 
     
     
       3. The nanocrystal particle of  claim 2 , wherein the first nanocrystal comprises a Group II-VI compound, a Group III-V compound, a Group IV-VI compound, a Group IV compound, or a combination thereof. 
     
     
       4. The nanocrystal particle of  claim 2 ,
 wherein the shell has a composition which is different than that of the first nanocrystal, 
 wherein the shell comprises a Group II-VI compound, a Group III-V compound, a Group IV-VI compound, a Group IV compound, a metal fluoride, a metal oxide, or a combination thereof, and 
 wherein the shell has a bandgap which is greater than a band gap of the first nanocrystal. 
 
     
     
       5. The nanocrystal particle of  claim 2 , wherein the boron is included in the core, an interface between the core and the shell, the shell, or combination thereof. 
     
     
       6. The nanocrystal particle of  claim 5 ,
 wherein the shell is a multi-layered shell having at least two layers, 
 wherein each of the layers is the same or different, and 
 wherein the boron is included in an inner layer of the shell, an outer layer of the shell, or a combination thereof. 
 
     
     
       7. The nanocrystal particle of  claim 2 , wherein the fluorine is included in the core, an interface between the core and the shell, the shell, or a combination thereof. 
     
     
       8. The nanocrystal particle of  claim 7 , wherein the boron and the fluorine are present in a same region of the nanocrystal particle. 
     
     
       9. The nanocrystal particle of  claim 7 , wherein the boron and the fluorine are present in different regions of the nanocrystal particle. 
     
     
       10. The nanocrystal particle of  claim 7 ,
 wherein the shell is a multi-layered shell having at least two layers, 
 wherein each of the layers is the same or different, and 
 wherein the fluorine is included in an inner layer of the shell, an outer layer of the shell, or a combination thereof, and 
 wherein the fluorine and the boron are present in a same layer or in different layers from each other. 
 
     
     
       11. The nanocrystal particle of  claim 1 , wherein the organic ligand comprises a compound of the formula RCOOH, RNH 2 , R 2 NH, R 3 N, RSH, RH 2 PO, R 2 HPO, R 3 PO, RH 2 P, R 2 HP, ROH, RCOOR′, RPO(OH) 2 , or R 2 POOH, wherein R and R′ are each independently a C1 to C24 alkyl group, a C2 to C24 alkenyl group, or a C6 to C20 aryl group, or a combination thereof. 
     
     
       12. The nanocrystal particle of  claim 1 , wherein an amount of the boron ranges from about 0.1 mole percent to about 50 mole percent, based on a total moles of all elements included in the nanocrystal particle. 
     
     
       13. The nanocrystal particle of  claim 1 , wherein the amount of the fluorine is greater than 0 mole percent and less than or equal to about 30 mole percent, based on a total moles of all elements included in the nanocrystal particle. 
     
     
       14. The nanocrystal particle of  claim 1 , wherein a mole ratio between the boron and the fluorine is about 1:100 to about 1:0.1. 
     
     
       15. A plurality of the nanocrystal particles of  claim 1 , wherein the plurality of the nanocrystal particles exhibits a quantum yield of greater than or equal to about 65 percent and has a standard deviation of a particle size of less than or equal to about 20 percent. 
     
     
       16. A device comprising the nanocrystal particle of  claim 1 . 
     
     
       17. The device of  claim 16 , wherein the device is a light emitting diode, an organic light emitting diode, a sensor, a solar cell electronic device, or a liquid crystal display. 
     
     
       18. A process of synthesizing the nanocrystal particle of  claim 1 , the process comprising:
 obtaining a first mixture including a first precursor, a ligand compound, and a solvent; 
 optionally heating the first mixture; 
 adding a boron source, a second precursor, optionally a first nanocrystal, and a fluorine source to the optionally heated first mixture to obtain a second mixture; and 
 heating the second mixture to a reaction temperature to form a reaction product of the first precursor and the second precursor, wherein the reaction product is the nanocrystal particle of  claim 1 . 
 
     
     
       19. The process of synthesizing a nanocrystal particle of  claim 18 ,
 wherein the first precursor comprises a Group II metal, a Group III metal, a Group IV metal, or a combination thereof, and wherein the first precursor is in a form of an elemental metal, an alkylated metal compound, a metal alkoxide, a metal carboxylate, a metal nitrate, a metal perchlorate, a metal sulfate, a metal acetylacetonate, a metal halide, a metal cyanide, a metal hydroxide, a metal oxide, a metal peroxide, or a combination thereof, and 
 wherein the second precursor comprises a Group V element, a compound comprising a Group V element, a Group VI element, a compound comprising a Group VI element, or a combination thereof. 
 
     
     
       20. The process of synthesizing a nanocrystal particle of  claim 18 , wherein the ligand compound comprises a compound of the formula RCOOH, RNH 2 , R 2 NH, R 3 N, RSH, RH 2 PO, R 2 HPO, R 3 PO, RH 2 P, R 2 HP, ROH, RCOOR′, RPO(OH) 2 , or R 2 POOH, wherein R and R′ are each independently a C1 to C24 alkyl group, a C2 to C24 alkenyl group, or a C6 to C20 aryl group, or a combination thereof. 
     
     
       21. The process of synthesizing a nanocrystal particle of  claim 18 , wherein the solvent comprises a C6 to C22 primary amine, a C6 to C22 secondary amine, C6 to C40 tertiary amine, a heterocyclic compound comprising a nitrogen atom, a C6 to C40 olefin, a C6 to C40 aliphatic hydrocarbon, a C6 to C30 aromatic hydrocarbon substituted with a C1 to C20 alkyl group, a primary, secondary, or tertiary phosphine comprising at least one C6 to C22 alkyl group, a primary, secondary, or tertiary phosphine oxide having at least one C6 to C22 alkyl group, a C12 to C22 aromatic ether, or a combination thereof. 
     
     
       22. The process of synthesizing a nanocrystal particle of  claim 18 , wherein the boron source comprises a complex of borane and a substance having a lone pair of electrons. 
     
     
       23. The process of synthesizing a nanocrystal particle of  claim 22 , wherein the substance having a lone pair of electrons comprises a C1 to C16 amine, a C2 to C16 ether, a C3 to C16 carbonyl containing compound, tetrahydrofuran, a C2 to C16 alkyl sulfide, an a C7 to C20 arylmethyl sulfide, an C3 to C30 allylmethyl sulfide, tetrahydrothiophene, pyridine, PF 3 , H − , or a combination thereof. 
     
     
       24. The process of synthesizing a nanocrystal particle of  claim 18 , wherein the fluorine source comprises HF, NH 4 F, LiF, NaF, KF, BeF 2 , M g F 2 , CaF 2 , SrF 2 , CuF, CuF 2 , AgF, AuF, AuF 3 , ZnF 2 , CdF 2 , HgF 2 , AIF 3 , GaF 3 , InF 3 , SnF 2 , PbF 2 , BF 3 , HBF 4 , a BF 4   − -containing salt, a PF 6   − -containing salt, B(Ar) 3  wherein Ar is a fluorine substituted C6 to C20 aromatic hydrocarbon group, or a combination thereof. 
     
     
       25. The process of synthesizing a nanocrystal particle of  claim 18 , wherein the boron source and the fluorine source comprise a single compound comprising boron and fluorine. 
     
     
       26. The process of synthesizing a nanocrystal particle of  claim 25 , wherein the single compound comprising boron and fluorine comprises BF 3 , HBF 4 , NaBF 4 , NH 4 BF 4 , alkylammonium tetrafluoroborate, an ionic liquid, or a combination thereof. 
     
     
       27. The process of synthesizing a nanocrystal particle of  claim 18 , wherein the boron source and optionally the fluorine source are each added to the first mixture in an amount of 0.5 mole percent to 500 mole percent, based on total moles of the first precursor.